Middle-ear disease is the cause of conductive hearing losses that affect nearly every person in the world at some time in their life. Most of these cases are due to acute infectious processes that are amenable to antibiotic treatment and are quickly resolved. However, a sizable fraction of these cases are due to chronic middle-ear disease, which is best treated by middle-ear surgery, i.e., opening of the mastoid to remove disease (mastoidectomy) and reconstruction of all or part of the middle-ear sound-conductive apparatus (tympanoplasty). There are over 70,000 middle-ear surgeries performed each year in the US.
While middle-ear disease is common, the differential diagnosis of the multiple pathologies responsible for these hearing losses is problematic. Even diagnosis of the common middle-ear effusion depends on expert observation or the use of screening systems that generate significant high false positive rates. Differential diagnosis of the pathology responsible for conductive hearing loss with an intact eardrum (tympanic membrane) and fluid-free middle ear is a particularly difficult problem, even for a trained otologist. Furthermore, while the surgery to cure ears of chronic disease is highly successful, the hearing results of middle-ear reconstructive procedures are generally poor, except for certain minimally invasive procedures such as stapes replacement surgery (stapedectomy).
Otoscopy and pneumatic otoscopy work well for the diagnosis of middle-ear effusion in well-trained hands, but the average clinician is not always capable of accurately performing these tests. Simple otoscopy is of little value in the diagnosis of ossicular disorders; pneumatic otoscopy is useful in expert hands, but the assessment of eardrum mobility is subjective and such expertise is not easy transferred to inexperienced clinicians. In the hands of a practiced observer, pneumatic otoscopy can sometimes aid in the diagnosis of reconstructive failures.
Tympanometry (and its cousin reflectometry) is one of the standard screening methods for the presence of middle-ear effusion. As a screener, tympanometry is fairly sensitive for middle ear effusion, but of less than perfect selectivity (there is a sizable percentage of false positives). The utility of tympanometry in differential diagnosis of ossicular disorders or evaluation of middle-ear reconstruction is limited. Tympanometry also shows limited sensitivity and selectivity in cases of ossicular disorders or chronic middle-ear disease.
Laser-Doppler vibrometry (LDV) has been successfully used in the differential diagnosis of ossicular disorders and the evaluation of middle-ear reconstructive procedures. It presently requires two people (a clinician observer and a computer operator) to make these measurements.
Therefore, there is a need for systems and methods for the observation of middle ear behavior that provide easier use and accurate measurements.